Monaco, often called “Le Rocher” (The Rock) is officially the Principauté de Monaco, a sovereign city-state and the second smallest microstate after the Vatican. France borders the country on three sides while the other side borders the Mediterranean Sea. Monaco has an area of 2.02 km2 (0.78 sq mi) and, with a population of about 38,400 (over 19,009 inhabitants per km²), it is also the most densely populated country in the world.